Tasmanian businesses and residents have complained about NBN connection delays.

Reuters

The Federal Communications Minister, Malcolm Turnbull, has denied allegations that the company rolling out the NBN in Tasmania was ordered not to speak to a Senate inquiry.

The Senate Select Committee into the NBN is conducting hearings in Hobart today.

Businesses and residents have complained their connection to the network is being delayed.

The NBN was supposed to be delivered by late next year, but only 10,000 Tasmanians are connected so far.

Committee member and former Labor minister, Stephen Conroy, has blamed the Coalition Government for the slowdown in the Tasmanian rollout.

He said it would have been completed by now if all the original contracts signed by his Government had been honoured.

He also accused Mr Turnbull of blocking Tasmanian contractor Visionstream from testifying.

"Visionstream have written to the inquiry saying NBN won't allow us to testify...this isn't good enough," he said.

"Malcolm Turnbull can make all the political statements he wants, the committee wants to call Visionstream to get to the bottom of this accusation, and Visionstream aren't allowed to appear.

"This is not an acceptable way for NBN to do business, to gag its contractors so they can't appear before the committee...let them tell their side of the story instead of Malcolm Turnbull gagging them in public and then and saying it is all their fault."

The company was given the option of giving evidence in-camera.

But Visionstream says confidentiality rules which cover its NBN work mean it would not be able to give the detailed evidence required.

Rollout back on track: Turnbull

Mr Turnbull said Senator Conroy was seeking to divert attention from his own responsibility for problems with the NBN rollout.

He insisted work on the Tasmanian rollout was back on track and said the rollout had been plagued with stoppages under Labor.

He said the optic fibre cable now runs past 32,000 homes and another 17,000 would have access shortly.

A further 19,000 homes were in the planning and remediation stage.

The Minister says Visionstream has two regional offices in Tasmania with 200 people working on the rollout.

Liberal committee member Senator Zed Seselja told the hearing NBN contracts were under review because Labor left the network in a mess when it lost office last year.

He would not say when the network would be delivered in Tasmania.

He said the committee hearings so far had just been an attempt by Labor and the Greens to score political points.